Spotted at the library and likely published no more than 5 years ago, I don't have much to go on, but: it's set in the country or a small town in the Midwest, possibly Minnesota. I'm not entirely sure what the main plot is but I know the main character is a girl with a steady boyfriend, only she keeps spending all her time with a New Boy, who is harboring a dark personal secret, which I think involves his sister.
The cover was predominantly a dark blue, possibly an outdoor shot at night. Unfortunately, this was a library I'd never been in before that has just closed to move to a new building, so I don't remember where the in alphabet the author's name was except it wasn't between K and N.
Hah, hah, okay...clearly no one should ever depend on me as a witness, and I don't think anyone would have gotten it based on these extra thin details. But after a painstaking year-by-year search of every teen book in the library system's online catalog, I've identified it as Truest by Jackie Lea Sommers. Whose cover is in fact an outside shot, but in full daylight.
Yeah lol, I wanted to help but an YA set in a small town with a love triangle? And a brooding guy with a dark past? Would have been faster to find an YA novel without those elements :p
The cover was predominantly a dark blue, possibly an outdoor shot at night. Unfortunately, this was a library I'd never been in before that has just closed to move to a new building, so I don't remember where the in alphabet the author's name was except it wasn't between K and N.